New Organization Provides Efficiency Ranking of Supercomputers

For computer experts focused solely on performance, June and November
mark the twice-yearly release of the TOP500 list, which ranks the
world's supercomputers in terms of "teraflops," or trillions of
calculations per second (the "flop" comes from "floating-point
operations," a technical term for computer calculations). That list is
currently led by a supercomputer at DOE's Lawrence Livermore National
Laboratory (LLNL) that has a peak speed of more than 596 teraflops.
But the November 2007 list of supercomputing speed freaks was accompanied
by a newcomer, the Green500 list, which reworks the TOP500 list in
terms of energy efficiency. The Green500 list ranks the 500 fastest
supercomputers by megaflops per watt, that is, by how many thousands
of calculations are performed per watt of energy consumed.

On the Green500 list, a research computer run by the United Kingdom's
Science and Technology Council takes first place with 357 megaflops
per watt, while the LLNL computer drops to 22nd place with only
205 megaflops per watt. But IBM has plenty to crow about in either
case, having provided both the LLNL computer and 26 of the 27 top
computers on the Green500 list. According to IBM, its Blue Gene/P
supercomputers achieve high efficiency through their dense packaging
of processors, memory, and interconnects. By the way, the number five
supercomputer on the Green500 list is located at DOE's Oak Ridge
National Laboratory. See the TOP500 list, the Green500 list, and the
IBM press release.